Green Spain really starts at the divide between Castilla y León and Cantabría. Although the Picos de Europa have achieved just fame, there are other spectacular vistas awaiting the adventurous traveller. We turned north from Espinosa de Los Monteros, Burgos Province, to climb over the divide at Portillo de La Sía and an abrupt and sinuous descent into Cantabria at Los Collados de Ason. Later, we crested Puerto de Alisas for a fine 360º view.